A FOTHERINGHAM1,2,3, L BALMER4,5, Q NGUYEN4, R WHIDDETT1,3, X-M CHEN6, C POLLOCK6, G MORAHAN4, J FORBES1,2,3
1Mater Research Institute-The University of Queensland, TRI, Brisbane, Australia, 2Faculty of Medicine, The University of Queensland, Brisbane, Australia, 3Translational Research Institute , Brisbane, Australia, 4Centre for Diabetes Research, Harry Perkins Institute of Medical Research, Australia Centre of Medical Research, University of Western Australia, Nedlands, Australia, 5School of Medical and Health Sciences, Edith Cowen University, Joondalup, Australia, 6Renal Research Laboratory, Kolling Institute of Medical Research, The University of Sydney, Royal North Shore Hospital, St Leonards, Sydney, Australia
Aim: To identify novel genes associated with GFR using the Collaborative Cross (CC) gene mine.
Background: The heritability of CKD is estimated to be high (30-75%), suggesting genetic factors play an important role. The CC gene mine is a murine genetic reference population established by a global consortium for simple and rapid quantitative trait loci (QTL) mapping. Here, we have used the CC reference platform to identify novel loci associated with renal function using circulating cystatin C as a surrogate for GFR.
Methods: CC mice were housed at the Animal Resource Centre, WA. Serum was collected from 67 of the CC strains and 4 founder strains (32 and 65 days of age) and cystatin C measured by ELISA. QTL mapping was performed using a SNP-wise haplotype analysis to identify genetic loci associated with circulating cystatin C. Six genes located within candidate regions were examined further by qPCR in models of diabetic kidney disease (db/db and eNOS-/- + streptozotocin-induced diabetes) and adenine induced nephropathy.
Results: Serum cystatin C concentrations ranged from 443.8 ng/ml to 953.8 ng/ml in the strains analysed. Haplotype and genome wide screening identified loci, on Chromosome 10 and Chromosome 17 that associated with circulating levels of cystatin C (LOD>8, p=<0.001 and LOD>7, p<0.01 respectively). Two candidate genes, one at each loci, show evidence for an association between gene expression levels, with GFR and incident kidney disease in a preliminary screen of models of kidney disease and injury.
Conclusions: We have identified regions on chromosome 10 and chromosome 17 that associate with renal function as measured by cystatin C. We are further investigating candidate genes located at these loci.
Amelia Fotheringham recently graduated from her PhD with the Glycation and Diabetes Complications Group at Mater Research Institute-The University of Queensland, under the guidance of Professor Josephine Forbes. Her research focuses on dietary factors and their role in kidney disease. Her research encompasses dietary advanced glycation end products, examining their uptake and trafficking from the diet. Additionally, through collaborations with the Charles Perkins Centre and the Harry Perkins Institute of Medical Research she is utilising novel mouse resources such as the Collaborative Cross and the Geometric Framework for Nutrition to explore genetic and dietary influences on kidney health and ageing.